def test_apply():
a = Series("a", [1, 2, None], nullable=True)
b = a.apply(lambda x: x**2)
assert b == [1, 4, None]
a = Series("a", ["foo", "bar", None], nullable=True)
b = a.apply(lambda x: x + "py")
assert b == ["foopy", "barpy", None]
b = a.apply(lambda x: len(x), dtype_out=Int32)
assert b == [3, 3, None]
b = a.apply(lambda x: len(x))
assert b == [3, 3, None]
def my_custom_func(s: pl.Series) -> pl.Series:
return s.apply(lambda x: my_map[x])
